German Server 2019 CU12 here, Aug23SU was installed automatically on 09. Aug 03:30am without issue.
Well actually it says in the ExchangeSetupLogs\ServiceControl.log that our AV service failed to stop:
[02:55:10] Fehler beim Beenden des Diensts 'Sophos Managed Threat Response'. Fehler: 'Der Dienst Sophos Managed Threat Response auf dem Computer . kann nicht beendet werden.'.
[02:55:10] Unable to stop all services for AdminTools ClientAccess FrontendTransport Bridgehead Mailbox.
But HealthChecker reports Aug23SU is installed and binaries are version 15.2.1118.36.
I don't want to brag, but I already had this server left with all Exchange services disabled when the last update failed to install - so, basically before it was cool.